Resistin, Obesity, and Insulin Resistance — The Emerging Role of the Adipocyte as an Endocrine Organ

Adipose tissue is an endocrine organ secreting biologically active factors called adipokines that act on both local and distant tissues. Adipokines have an important role in the development of obesity-related comorbidities not only in adults but also in children and adolescents. Retinol binding protein 4 (RBP4) is a recently identified adipokine suggested to link obesity with its comorbidities, especially insulin resistance, type 2 diabetes (T2D), and certain components of the metabolic syndrome. However, data, especially resulting from the clinical studies, are conflicting. In this review, we summarize up-to-date knowledge on RBP4's role in obesity, development of insulin resistance, and T2D. Special attention is given to studies on children and adolescents. We also discuss the role of possible confounding factors that should be taken into account when critically evaluating published studies or planning new studies on this exciting adipokine.

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Adipose-Derived Exosomes as Possible Players in the Development of Insulin Resistance

International Journal of Molecular Sciences ◽

10.3390/ijms22147427 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7427

Author(s):

Arkadiusz Żbikowski ◽

Agnieszka Błachnio-Zabielska ◽

Mauro Galli ◽

Piotr Zabielski

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

Metabolic Disorders ◽

Biologically Active ◽

Whole Body ◽

Secretory Function ◽

Endocrine Organ ◽

Actual Knowledge ◽

Whole Body Metabolism

Adipose tissue (AT) is an endocrine organ involved in the management of energy metabolism via secretion of adipokines, hormones, and recently described secretory microvesicles, i.e., exosomes. Exosomes are rich in possible biologically active factors such as proteins, lipids, and RNA. The secretory function of adipose tissue is affected by pathological processes. One of the most important of these is obesity, which triggers adipose tissue inflammation and adversely affects the release of beneficial adipokines. Both processes may lead to further AT dysfunction, contributing to changes in whole-body metabolism and, subsequently, to insulin resistance. According to recent data, changes within the production, release, and content of exosomes produced by AT may be essential to understand the role of adipose tissue in the development of metabolic disorders. In this review, we summarize actual knowledge about the possible role of AT-derived exosomes in the development of insulin resistance, highlighting methodological challenges and potential gains resulting from exosome studies.

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Fat as an endocrine organ: influence of exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.00134.2005 ◽

2005 ◽

Vol 99 (2) ◽

pp. 757-764 ◽

Cited By ~ 45

Author(s):

Jason R. Berggren ◽

Matthew W. Hulver ◽

Joseph A. Houmard

Keyword(s):

Insulin Resistance ◽

Insulin Sensitivity ◽

Insulin Action ◽

Endocrine Organ ◽

Pathological Conditions ◽

Obesity And Diabetes ◽

Strong Candidate ◽

Novel Target ◽

Diabetes And Obesity

The prevalence of diabetes and obesity continues to increase. It is therefore important to identify the pathophysiology underlying these disorders. An inability of insulin to stimulate glucose uptake, i.e., insulin resistance, appears to be a common link between diabetes and obesity. The identification of various adipocyte-secreted cytokines (adipocytokines) that influence satiety, energy balance, and insulin sensitivity provide a novel target for the treatment of these disorders. Adipocytokines are differentially expressed with obesity and diabetes, making them a strong candidate for linking insulin resistance to these pathological conditions. This review explores the role of adipocytokines in insulin action and examines the effect of exercise training on adipocytokine content.

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Adipokines in Insulin Resistance: Current Updates

Biosciences Biotechnology Research Asia ◽

10.13005/bbra/2922 ◽

2021 ◽

Vol 18 (2) ◽

pp. 357-366

Author(s):

Utpal Jagdish Dongre

Keyword(s):

Insulin Resistance ◽

Signalling Pathways ◽

Tnf Alpha ◽

Insulin Receptor Substrate ◽

Lipocalin 2 ◽

Endocrine Organ ◽

Signalling Molecules ◽

Metabolic Signalling ◽

Primary Mechanism

Obesity is a chronic metabolic disease that affects both the pediatric and adult populations. Adipose tissue acts as an endocrine organ which secretes various adipokines involved in fat mass regulation and energy balance via modulating the metabolic signalling pathways. Altered secretion of adipokines promotes multiple complications, including insulin resistance. The primary mechanism of action that underlines the involvement of adipokines in the development of insulin resistance includes phosphorylation/de-phosphorylation of insulin receptor substrate-1 (IRS-1) facilitate by other signalling molecules like a suppressor of cytokine signalling 1 (SOCS-1). Adipokines mediated insulin resistance further contribute to the development of atherosclerosis, dyslipidemia, fatty liver disease, cancer etc. Thus, this review provides recent updates on the role of resistin, lipocalin-2, RBP-4, chemerin, TNF-alpha and IL-6 adipokines in the progression of insulin resistance.

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